The invention is related to a brake pressure control device for a hydraulic vehicle brake unit with a valve arrangement being actuatable by a brake pedal by means of which a hydraulic fluid outlet for the connection of a brake circuit is connectible alternately either to a reservoir or to a pressure source.
An example of brake pressure control device of this type is shown in U.S. Pat. No. 4,705,324. Such brake pressure control devices supply pressurized hydraulic fluid from a pressure source, such as a pump or pressure accumulator in a controlled manner to one or more brake circuits, depending on an actuating force exerted on a brake pedal in order to generate a braking effect at the brakes of a vehicle which is proportional to the actuating force. Brake pressure control devices of this kind are frequently employed in brake units which are equipped with a brake slip control by which the locking of the vehicle wheels during a braking action is prevented. In the prior-art brake pressure control devices, solenoid valves are provided for achieving a brake slip control which are actuated by an electronic anti-locking device in order to separate the brake circuit from the hydraulic fluid outlet and to connect it to the reservoir and in this way to attain a pressure reduction in the brake circuit. By switching the solenoid valves back into the starting position, the brake circuit is connected again to the hydraulic fluid outlet of the brake pressure control valve for a pressure build-up.
It is the object of the present invention to create a brake pressure control device of the type described which affords a control of the brake pressure by an electronic control device without the necessity of additional solenoid valves.